round metal ductwork sweating: what insulation

[vdotmatrix]

Last summer I noticed brown stains on the ceiling tile in the basement, below the HVAC ductwork. This is round sheet metal running the length of a joist to the register that feeds the upstairs room....when it is extremely hot and/or humid I suspect dew point is reached and Houstin we have a problem.

So with this issue, I want to insulated any duct work that is accessible. Should I just seal the joist with regular R13 and seal the ductwork or find some kind of ductwork wrap that I wrap and staple the ductwork?

What is the solution...

[LazyPup]

You can use foil backed fiberglass and tape all the seams with the foil tape.

[pushkins]

I wouldn't fill the joist space with R13.
You can buy at the big boy hardware stores "duct wrap" (I just noticed before it was to late I typed Duc"k" wrap) insulation. Wrap the ducks as best you can with this insulation trying to cover the entire exposed duct, this should solve your problem.
Doing it this way is safer than just jamming the joist full, because if there is still a problem a much larger area of the R13 will absorb the moisture long before you notice any problem.

[vdotmatrix]

do you have a brand name?